Flavobacterium degerlachei sp. nov., Flavobacterium frigoris sp. nov. and Flavobacterium micromati sp. nov., novel psychrophilic bacteria isolated from microbial mats in Antarctic lakes

Abstract

Taxonomic studies were performed on 36 strains that were isolated from microbial mats in Antarctic lakes of the Vestfold Hills, the Larsemann Hills and the McMurdo Dry Valleys. Phylogenetic analysis based on 16S rRNA gene sequences indicated that these strains are related to members of the genus Flavobacterium; sequence similarity values with their nearest phylogenetic neighbours ranged from 96·8 to 98·5 %. Results of DNA–DNA hybridization and comparison of repetitive extragenic palindromic DNA-PCR fingerprinting patterns revealed that these strains are members of three distinct species. Genotypic results, together with phenotypic characteristics, allowed the differentiation of these species from related Flavobacterium species with validly published names. The isolates are Gram-negative, chemoheterotrophic, rod-shaped cells that are psychrophilic and moderately halotolerant; their DNA G+C contents range from 33·1 to 34·5 mol%. Their whole-cell fatty acid profiles are similar and include C15 : 0, anteiso-C15 : 0, iso-C15 : 0, C15 : 1 ω6c, iso-C16 : 0, iso-C16 : 0 3-OH and summed feature 3 (which comprises iso-C15 : 0 2-OH, C16 : 1 ω7c or both) as major fatty acid components. On the basis of these results, three novel species are proposed, namely Flavobacterium degerlachei sp. nov. (consisting of 14 strains, with LMG 21915T=DSM 15718T as the type strain), Flavobacterium micromati sp. nov. (consisting of three strains, with LMG 21919T=CIP 108161T as the type strain) and Flavobacterium frigoris sp. nov. (consisting of 19 strains, with LMG 21922T=DSM 15719T as the type strain).

Flavobacterium saliperosum sp. nov., isolated from freshwater lake sediment

“…Flavobacterium species are physiologically diverse: they can be psychrophilic, psychrotolerant or mesophilic, and can be halophilic, halotolerant or sensitive to salts. As a reflection of their physiological diversity, Flavobacterium species have been isolated from various habitats such as freshwater sediments and soil (Bernardet et al, 1996;Tamaki et al, 2003;McCammon & Bowman, 2000), a glacier (Zhu et al, 2003) and Antarctic lakes (Van Trappen et al, 2003, 2004McCammon et al, 1998;McCammon & Bowman, 2000;Humphry et al, 2001;Yi et al, 2005).…”

Flavobacterium fryxellicola sp. nov. and Flavobacterium psychrolimnae sp. nov., novel psychrophilic bacteria isolated from microbial mats in Antarctic lakes

“…Members of the phylum Bacteroidetes are abundant in freshwater and marine ecosystems and these bacteria may have a specialized role in the uptake and degradation of organic matter in cold, aquatic environments (Kirchman, 2002). Several novel species, added to the genus Flavobacterium since 1996, have originated from Antarctic habitats (Van Trappen et al, 2003, 2004; and references cited therein).…”

“…Members of the phylum Bacteroidetes are abundant in freshwater and marine ecosystems and these bacteria may have a specialized role in the uptake and degradation of organic matter in cold, aquatic environments (Kirchman, 2002). Several novel species, added to the genus Flavobacterium since 1996, have originated from Antarctic habitats (Van Trappen et al, 2003, 2004; and references cited therein).During the MICROMAT project (November 1998-February 2001, 746 bacterial strains were isolated under heterotrophic conditions from microbial mat samples that were collected from ten Antarctic lakes (Van Trappen et al, 2002). Numerical analysis of the fatty acid composition of the isolates and 16S rRNA gene sequence analysis, performed on representative strains, showed that the diversity of heterotrophic bacteria in microbial mats from Antarctic lakes is very high.…”

“…Moreover, many fatty acid clusters were shown to contain multiple taxa when tested by repetitive extragenic palindromic DNA-PCR (rep-PCR) fingerprinting, a technique used to investigate the genomic diversity of each fatty acid cluster in more detail (Van Trappen et al, 2003, 2004. Several strains belonging to fatty acid clusters 5, 6 and 10 have previously been described as novel Flavobacterium species: Flavobacterium gelidilacus, Flavobacterium degerlachei, Flavobacterium frigoris and Flavobacterium micromati (Van Trappen et al, 2003, 2004.In the present work, the taxonomic relationships of 22 strains from fatty acid cluster 5 (as delineated by Van Trappen et al, 2002) were studied. A group of 11 of these strains was identified as Flavobacterium xanthum, whereas another rep-cluster of four strains was identified as the recently described species F. frigoris (Van Trappen Table B, could be divided into two different clusters according to their profile type (see Fig.…”

“…These clusters are hereafter referred to as rep-PCR profile type I (comprising three strains) and type II (with four strains) (see Table B). Almost-complete 16S rRNA gene sequences (1466-1479 nt) of strains LMG 22022 T , LMG 22018 T , LMG 22020, R-9010 and R-7518 were determined as described previously (Van Trappen et al, 2004). The most closely related sequences were found using the program FASTA; sequences from reference strains were aligned, and editing of the alignment and reformatting was performed with the programs BIOEDIT (Hall, 1999) et al, 1996;Van Trappen et al, 2003).…”